1. Field of the Invention
The present invention relates to an image scanning apparatus for use in image readers, copying machines and the like, and more particularly to an image scanning apparatus for scanning the image of a document by moving a light source along the document image.
2. Description of the Prior Art
For use in image readers and the like, various image scanning apparatus have heretofore been proposed in which the image of a document is scanned and exposed by the movement of a light source along the document.
FIG. 1 is a block diagram conceptionally showing the construction of a conventional image scanning apparatus of the type stated above. The apparatus comprises a light source 170 for illuminating the document surface, movable means (slider) 101 supporting the light source 170 thereon and movable along the document surface, drive means 140 for supplying high-voltage current to the light source 170 to light the light source 170, control means (not shown) for controlling the drive means 140, and means for supplying electric power. The drive means 140 is fixedly mounted on the body of the apparatus and connected to the light source 170 through a harness which includes a bundle of cables such as signal wires, electric power supply line and the like.
A heater 183 is provided around the light source 170 when required for improving the light-intensity rise characteristics of the light source.
With the conventional apparatus, the light source 170, the heater 183, etc. are mounted, in the form of a unit, on the movable means 101, while the drive means 140 is mounted on the body of the apparatus and connected to the light source 170 by the harness through which high-voltage current flows as described above.
Accordingly, full care must be taken in handling the harness connecting the movable means (light source and heater) 101 to the fixed body (drive means).
For example, since the high-voltage current for driving the light source 170 flows through the harness, the components or members around the harness need to have sufficient insulating properties.
The harness, which is connected at its one end to the movable means 101, is continually deformed with the travel of the movable means and is therefore required to have high flexibility and also sufficient strength against a break due to the deformation.
The harness includes the high-voltage line (power line) for driving the light source in combination with the control signal wires and consequently has the problem that the control signal is liable to pick up noises.
Nevertheless, it is economically disadvantageous to use materials of sufficient insulating propertes around the harness.
Additionally, with a tendency to use a plurality of light sources and to resort to a more complex mode of control, there is a tendency to incorporate an increased number of wires or cables into the harness. It is therefore difficult to give high flexibility to the harness.